Wireless networks continue to evolve as new communication technologies develop and standardize. Current wireless network deployments include many variations in architecture, including support for different wireless communication technologies offered by one or more wireless network service providers. A representative wireless network for a wireless network service provider can include support for one or more releases of wireless communication protocols specified by the Third Generation Partnership Project (3GPP) and Third Generation Partnership Project 2 (3GPP2) communication standards organizations. The 3GPP develops mobile communication standards that include releases for Global System for Mobile Communications (GSM), General Packet Radio Service (GPRS), Universal Mobile Telecommunications System (UMTS), Long Term Evolution (LTE) and LTE Advanced standards. The 3GPP2 develops wireless communication standards that include CDMA2000 1×RTT and 1×EV-DO standards. Newer wireless communication protocols include options for transmission and reception using multiple antennas, and mobile wireless devices can include several antennas located in different areas of the mobile wireless device to improve transmission and reception performance. While multiple antenna reception in a mobile wireless device can be used in certain wireless communication protocols for downlink transmission, multiple antenna uplink transmission can be precluded for the mobile wireless device. The mobile wireless device, however, can select between multiple antennas for single antenna transmission to provide improved uplink performance.
In a mobile wireless device with multiple antennas, radio frequency transmission and reception impairments, such as a user's hand grip on the mobile wireless device, can cause an imbalance in received downlink signal power levels between the different antennas. This radio frequency impairment can also impact uplink transmissions, resulting in a degradation of the transmitted signals from the mobile wireless device to the wireless network. Switching transmission among the multiple antennas can provide improved performance; however, the selection of which antenna to use can be complicated by the irregular transmission characteristics of data traffic. For a voice connection, transmission of voice packets can be approximately continuous, and thus an uplink transmit power can be monitored to determine which antenna to use. In contrast, for a data connection, transmission of data packets can be irregular, and the uplink transmit power levels can vary significantly during the data connection. Thus, there exists a need for a method to select transmit antennas a mobile wireless device based on a set of monitored receive and transmit radio frequency signal characteristics.